Abstract：Autism spectrum disorder (ASD) is a neurodevelopmental disorder mainly characterized by social communication disorders, repetitive behaviors and narrow interests.The etiology of ASD is complex, and it focuses on the genetic and environmental factors.As the pathogenesis is unknown, there is no effective treatment.It is found that gastrointestinal diseases and changes of intestinal flora are common in ASD children.Recent studies have shown a two-way interaction between the gut nervous system and the central nervous system, called the microbiota-gut-brain axis.Gut flora regulates brain function through neuroendocrine, immune and intestinal nervous systems and thus affects brain development and behavior.Therefore, the imbalance of intestinal flora may be related to the occurrence of ASD.This article will summarize the effect of intestinal flora on ASD and the progress of related treatment.